Currently, with the progress and the improvement of technology, amount of information and amount of data of the content to be distributed from network side to a terminal (hereinafter referred as UE (User Equipment)) are rapidly increasing. Also, a technique is now growing popular to provide information to the users by combining different types of media together (media mix). Further, a system is known, which provides the content to each of the terminals by mutually changing the content at real time. In various types of communication service and user-participating type system, attempts are being made on coordination and unification of real-time broadcasting communication.
To operate in a system as such, UE is now capable to perform both the communication and the receiving of broadcasting. UE is so designed that a plurality of sessions can be managed and changed. As the technique to carry out the management of a plurality of sessions and to perform synchronizing processing, the techniques as disclosed in the following Patent Documents 1 and 2 are known.
For instance, the Patent Document 1 discloses a technique to carry out the session change to be executed and to maintain the application of a certain terminal while the application is carried out. Also, the Patent Document 2 discloses a technique of session mobility to shift a specific session at a certain terminal to another terminal.
Further, in the Non-Patent Document 1 as given below, SMIL (Synchronized Multimedia Integration Language) is disclosed, which describes a media synchronizing method on application layer. SMIL is a technology to synchronize by controlling reproduction of multimedia object (multimedia expression by descriptive language based on XML (Extensible Markup Language). According to SMIL, objects are specified by hyperlink. By describing time-related behavior of the objects to be synchronized (to display as to at which timing and how long) or layout (to which position it is to be displayed), well-synchronized multimedia objects can be reproduced.